/*
 * Copyright (c) 2018-2020 "Graph Foundation,"
 * Graph Foundation, Inc. [https://graphfoundation.org]
 *
 * This file is part of ONgDB.
 *
 * ONgDB is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
/*
 * Copyright (c) 2002-2020 "Neo4j,"
 * Neo4j Sweden AB [http://neo4j.com]
 *
 * This file is part of Neo4j.
 *
 * Neo4j is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package org.neo4j.shell.impl;

import java.io.Serializable;
import java.rmi.RemoteException;
import java.util.Map;

import org.neo4j.shell.CtrlCHandler;
import org.neo4j.shell.InterruptSignalHandler;
import org.neo4j.shell.Output;
import org.neo4j.shell.ShellClient;
import org.neo4j.shell.ShellException;
import org.neo4j.shell.ShellServer;

/**
 * A {@link ShellClient} implementation which uses a remote server,
 * where the output and session are remote also.
 */
public class RemoteClient extends AbstractClient
{
    private ShellServer server;
    private final RmiLocation serverLocation;
    private final Output out;

    public RemoteClient( Map<String,Serializable> initialSession, RmiLocation serverLocation,
            CtrlCHandler ctrlcHandler ) throws ShellException
    {
        this( initialSession, serverLocation, RemoteOutput.newOutput(), ctrlcHandler );
    }

    public RemoteClient( Map<String,Serializable> initialSession, RmiLocation serverLocation, Output output )
            throws ShellException
    {
        this( initialSession, serverLocation, output, InterruptSignalHandler.getHandler() );
    }

    /**
     * @param serverLocation the RMI location of the server to connect to.
     * @throws ShellException if no server was found at the RMI location.
     */
    public RemoteClient( Map<String,Serializable> initialSession, RmiLocation serverLocation, Output out,
            CtrlCHandler ctrlcHandler ) throws ShellException
    {
        super( initialSession, ctrlcHandler );
        this.serverLocation = serverLocation;
        this.out = out;
        this.server = findRemoteServer();
    }

    private ShellServer findRemoteServer() throws ShellException
    {
        try
        {
            ShellServer result = (ShellServer) this.serverLocation.getBoundObject();
            sayHi( result );
            updateTimeForMostRecentConnection();
            return result;
        }
        catch ( RemoteException e )
        {
            throw ShellException.wrapCause( e );
        }
    }

    @Override
    public Output getOutput()
    {
        return this.out;
    }

    @Override
    public ShellServer getServer()
    {
        // Poke the server by calling a method, f.ex. the welcome() method.
        // If the connection is lost then try to reconnect, using the last
        // server lookup address.
        boolean hadServer = this.server != null;
        boolean shouldTryToReconnect = this.server == null;
        try
        {
            if ( !shouldTryToReconnect )
            {
                server.welcome( initialSession );
            }
        }
        catch ( RemoteException | ShellException ignored )
        {
            shouldTryToReconnect = true;
        }

        Exception originException = null;
        if ( shouldTryToReconnect )
        {
            this.server = null;
            try
            {
                this.server = findRemoteServer();
                if ( hadServer )
                {
                    getOutput().println( "[Reconnected to server]" );
                }
            }
            catch ( ShellException | RemoteException ee )
            {
                // Ok
                originException = ee;
            }
        }

        if ( this.server == null )
        {
            throw new RuntimeException( "Server closed or cannot be reached anymore: " +
                    (originException != null ? originException.getMessage() : ""), originException );
        }
        return this.server;
    }

    @Override
    public void shutdown()
    {
        super.shutdown();
        tryUnexport( this.out );
    }
}
